Multi-component adhesive, in particular two-component adhesive, is generally applied using an adhesive gun consisting of two parallel cylindrical compartments: a first container for a first adhesive component and a second container for a second adhesive component. Generally, the first adhesive component contains constituents which cure when mixed with the second adhesive component. In general, the second adhesive component comprises a catalyst for the curing reaction, the curing reaction comprising, for example, a (co)polymerisation, crosslinking or vulcanization reaction. The adhesive gun to be used is in this case designed such that the two components are pressed out of the containers by means of plungers, with the two plungers being moved simultaneously in order to achieve a constant and uniform flow of both components from their containers. The two components are brought together in order to then be applied to a surface to be treated via a mixing unit of the adhesive gun. In order to achieve an optimum adhesive result, the two components must be mixed homogeneously, in which case an accurate mixing ratio is important.